The present invention relates generally to label laminates, and, more specifically, to manufacturing thereof.
The ubiquitous label laminate is found in various configurations for various uses, and is manufactured in various manners. The typical consumer label product is in the form of two-ply label sheet having multiple die cut labels removably bonded using pressure sensitive adhesive to an underlying liner coated with a release agent such as silicone.
The liner is typically mass produced in large rolls and then subsequently laminated to a face sheet also provided from large rolls. The laminated face sheet is then suitably die cut to define the individual labels thereon, with the laminate typically being produced in a continuous web which is then divided into sheets which are either cut or folded into stacked reams, or wound into a continuous roll.
Cut sheet labels are typically sold to consumers in stationery stores. The fan-fold and roll forms of label laminates are typically custom tailored for use by large commercial establishments for high speed use in large volume.
One variation of label laminates includes an integral form sheet extending in single ply from the two-ply laminate for providing a combined single sheet form/label configuration. These integrated sheets are typically custom tailored in configuration and size for the particular commercial customer. And, these integrated sheets are typically pre-printed with standard information such as company identification and other indicia indicative of the intended use of the sheet such as in commercial sales transactions.
The labels may be custom configured for customer and return address labels. The integral form may be configured for a packing list or invoice. And, in the typical pharmaceutical application, the various labels are specifically configured for identifying the particular pharmaceutical drug transaction, with the integral form containing use instructions and other details of the commercial drug purchase.
Since the integrated form/label sheet includes the two-ply label laminate and the adjoining single ply form sheet, the manufacture thereof is correspondingly complex, with associated cost. And, the combined one-ply and two-ply integrated sheet affects its subsequent use in printing by the intended customer in either small volume laser printers, for example, or in large volume high-speed printers.
As indicated above, pre-manufactured liner material may be laminated with pre-manufactured label material typically in continuous webs unwound from corresponding rolls. The singly ply form sheet may be suitably joined to the laminate with either a bonded lap-joint construction, or by integrating the form sheet with the face sheet defining the labels, with a liner patch laminated to the back side.
In this configuration, the liner and face sheet materials are fundamentally different from each other, even if made from ordinary paper. Ordinary paper is typically porous, which permits desirable printing thereon in various forms of printers. However, porous paper increases the difficulty of forming a suitable liner.
Liners are typically manufactured by applying a coating of liquid silicone which is then suitably cured, typically using ultraviolet (UV) light during the manufacturing process. If the paper is porous and readily absorbs the liquid silicone, the cured silicone may not form a suitable release coating for the pressure sensitive adhesive of the laminated face sheet.
Accordingly, liner material is typically formed from supercalendered kraft (SCK) paper which is pressed thinner than ordinary bond paper to prevent excess absorption of the liquid silicone during the manufacture of the release liner. In this way, a minimum amount of silicone will coat the SCK paper and will rapidly cure in the high-speed production transport thereof to form a smooth release surface having the desired release characteristics with the selected adhesive for permitting subsequent removal of individual adhesive labels therefrom.
The resulting integrated label/form sheet therefore includes a single ply face sheet for both the labels and form sheet, with a smaller patch of the thinner SCK liner bonded to the back side of the labels by the pressure sensitive adhesive laminated therebetween. Since the liner and face sheet have different material compositions and thicknesses, they are subject to undesirable curling thereof due to changes in temperature and relative humidity. Temperature and humidity cause the liner and face sheet to expand and contract differently from each other and leading to curl of the laminate which may cause misfeeding or jamming in typical printers.
One advantage of the edge joined laminate and form sheet is that a continuous web thereof may be driven through a printing press in a single pass for printing the front and back sides of the web at relatively low cost. In this way, the custom printed sheets may then be suitably packaged in stacks or rolls and sold to the corresponding commercial customer for subsequent use in laser printers or high-speed printers.
In another method of construction, the face sheet may be provided in a web and driven through the printer in one pass for printing thereof. The liner, in web form, may then be driven through the printer in another pass for printing the back side thereof as desired. And, the face sheet and liner are then laminated together with pressure sensitive adhesive therebetween in yet another processing step.
These multiple processing steps correspondingly increase the cost of production as opposed to the edge-joined production method disclosed above. However, the materials typically cost less in this multiprocess procedure as compared to the edge-joined procedure described above. Nevertheless, the multi-pass process typically results in the end product being more costly.
Accordingly, it is desired to provide an improved method of manufacturing label laminates, corresponding apparatus therefor, and the corresponding product produced thereby.